Visualizations of memory layouts in software programs

ABSTRACT

The disclosed embodiments provide a system that facilitates the execution of a software program. During operation, the system obtains a memory layout for an object instance in a software program, wherein the memory layout includes a set of offsets and a set of allocated sizes of a set of components associated with the object instance. Next, the system uses the memory layout to determine a first memory space occupied by data in the object instance and a second memory space occupied by padding in the object instance. The system then displays a visualization of the memory layout on the computer system, wherein the visualization includes a first graphical distinction between the first memory space and the second memory space.

RELATED APPLICATION

The subject matter of this application is related to the subject matterin a co-pending non-provisional application by the same inventors as theinstant application and filed on the same day as the instant applicationentitled “Context-Based Generation of Memory Layouts in SoftwarePrograms,” having Ser. No. 14/533,955, and filed on 5 Nov. 2014.

The subject matter of this application is also related to the subjectmatter in a co-pending non-provisional application by the same inventorsas the instant application and filed on the same day as the instantapplication entitled “Building Memory Layouts in Software Programs,”having Ser. No. 14/533,976, and filed on 5 Nov. 2014.

The subject matter of this application is also related to the subjectmatter in a co-pending non-provisional application by the same inventorsas the instant application and filed on the same day as the instantapplication entitled “Identifying Improvements to Memory Usage ofSoftware Programs,” having Ser. No. 14/533,955, and filed on 5 Nov.2014.

BACKGROUND

Field

The disclosed embodiments relate to techniques for improving memoryusage in software programs. More specifically, the disclosed embodimentsrelate to techniques for providing visualizations of memory layouts insoftware programs executing in virtual machines.

Related Art

Developers of software programs are typically unaware of how datastructures and/or objects in the software programs are laid out inmemory. As a result, the developers may create objects and/or datastructures that result in sub-optimal execution and/or memoryconsumption of the software programs. For example, a developer maydeclare fields in a software program without considering the alignmentrequirements of the fields, resulting in a greater amount of padding inthe software program than if the fields were declared in a differentorder and/or using different types. Because the padding representsmemory that does not contain useful data, the padding may unnecessarilyincrease the memory consumption of the software program and reduce thecache utilization of a processor on which the software program executes.

Consequently, the development and execution of software programs may befacilitated by mechanisms for improving the knowledge and management ofmemory consumption in the software programs.

SUMMARY

The disclosed embodiments provide a system that facilitates theexecution of a software program. During operation, the system obtains amemory layout for an object instance in a software program, wherein thememory layout includes a set of offsets and a set of allocated sizes ofa set of components associated with the object instance. Next, thesystem uses the memory layout to determine a first memory space occupiedby data in the object instance and a second memory space occupied bypadding in the object instance. The system then displays a visualizationof the memory layout on the computer system, wherein the visualizationincludes a first graphical distinction between the first memory spaceand the second memory space.

In some embodiments, the system also displays a memory consumption and apadding size of the object instance.

In some embodiments, the system also uses the memory layout to determinea first field associated with a first level of an inheritance hierarchyof the object instance and a second field associated with a second levelof the inheritance hierarchy. Next, the system includes a secondgraphical distinction between the first and second fields in thevisualization.

In some embodiments, the first graphical distinction includes adifference in transparency between the first and second memory spaces.

In some embodiments, the graphical distinction includes a difference incolor between the first and second memory spaces.

In some embodiments, the first memory space includes a header, metadata,and one or more fields.

In some embodiments, providing the visualization of the memory layout tothe user includes displaying the first and second memory spaces in agrid based on the set of offsets and the set of allocated sizes.

In some embodiments, the memory layout is associated with an executioncontext for the software program.

BRIEF DESCRIPTION OF THE FIGURES

The patent or application file contains at least one drawing executed incolor. Copies of this patent or patent application publication withcolor drawing(s) will be provided by the Office upon request and paymentof the necessary fee.

FIG. 1 shows a schematic of a system in accordance with the disclosedembodiments.

FIG. 2 shows the generation of a memory layout of an object instance ina software program in accordance with the disclosed embodiments.

FIG. 3 shows the identification of an improvement to the memory usage ofa software program in accordance with the disclosed embodiments.

FIG. 4A shows an exemplary screenshot in accordance with the disclosedembodiments.

FIG. 4B shows an exemplary screenshot in accordance with the disclosedembodiments.

FIG. 4C shows an exemplary screenshot in accordance with the disclosedembodiments.

FIG. 4D shows an exemplary screenshot in accordance with the disclosedembodiments.

FIG. 5 shows a flowchart illustrating the process of facilitating theexecution of a software program in accordance with the disclosedembodiments.

FIG. 6 shows a flowchart illustrating the process of facilitating theexecution of a software program in accordance with the disclosedembodiments.

FIG. 7 shows a flowchart illustrating the process of generating memorylayouts for a set of object instances in a software program inaccordance with the disclosed embodiments.

FIG. 8 shows a flowchart illustrating the process of generating memorylayouts for object instances in a software program in accordance withthe disclosed embodiments.

FIG. 9 shows a flowchart illustrating the process of using a set ofartifacts to generate a memory layout of an object instance representedby an artifact from the set of artifacts in accordance with thedisclosed embodiments.

FIG. 10 shows a flowchart illustrating the process of improving memoryusage in a software program in accordance with the disclosedembodiments.

FIG. 11 shows a flowchart illustrating the process of identifyinginefficient use of memory space in an object instance in a softwareprogram in accordance with the disclosed embodiments.

FIG. 12 shows a computer system in accordance with the disclosedembodiments.

In the figures, like reference numerals refer to the same figureelements.

DETAILED DESCRIPTION

The following description is presented to enable any person skilled inthe art to make and use the embodiments, and is provided in the contextof a particular application and its requirements. Various modificationsto the disclosed embodiments will be readily apparent to those skilledin the art, and the general principles defined herein may be applied toother embodiments and applications without departing from the spirit andscope of the present disclosure. Thus, the present invention is notlimited to the embodiments shown, but is to be accorded the widest scopeconsistent with the principles and features disclosed herein.

The data structures and code described in this detailed description aretypically stored on a computer-readable storage medium, which may be anydevice or medium that can store code and/or data for use by a computersystem. The computer-readable storage medium includes, but is notlimited to, volatile memory, non-volatile memory, magnetic and opticalstorage devices such as disk drives, magnetic tape, CDs (compact discs),DVDs (digital versatile discs or digital video discs), or other mediacapable of storing code and/or data now known or later developed.

The methods and processes described in the detailed description sectioncan be embodied as code and/or data, which can be stored in acomputer-readable storage medium as described above. When a computersystem reads and executes the code and/or data stored on thecomputer-readable storage medium, the computer system performs themethods and processes embodied as data structures and code and storedwithin the computer-readable storage medium.

Furthermore, methods and processes described herein can be included inhardware modules or apparatus. These modules or apparatus may include,but are not limited to, an application-specific integrated circuit(ASIC) chip, a field-programmable gate array (FPGA), a dedicated orshared processor that executes a particular software module or a pieceof code at a particular time, and/or other programmable-logic devicesnow known or later developed. When the hardware modules or apparatus areactivated, they perform the methods and processes included within them.

The disclosed embodiments provide a method and system for facilitatingthe execution of a software program. During development of the softwareprogram, source code for the software program may be created using aprogramming language. The source code may then be compiled into anexecutable form to enable the execution of the software program.

More specifically, the disclosed embodiments provide a method and systemfor improving memory usage in the software program. First, the disclosedembodiments provide functionality to generate memory layouts for objectinstances in the software program. Because the layout of the softwareprogram in memory may depend on the environment in which the softwareprogram is executed, the memory layouts may be generated by determiningthe structure of the software program and applying a given executioncontext from a set of possible execution contexts for the softwareprogram to the determined structure.

For example, the structure of the software program may be determined bycreating a set of logical representations of the object instances fromclass descriptions, compiled classes, and/or memory dumps associatedwith the software program. Next, the logical representations may beconverted into structural representations that contain standard binaryversions of components in the object instances. A virtual machineinstance may be configured to operate within the execution context, andthe structural representations may be provided to the virtual machineinstance for generation of the memory layouts from the structuralrepresentations. Memory layouts may be generated for other executioncontexts by configuring additional virtual machine instances to operatewithin the other execution contexts, providing the structuralrepresentations to the other virtual machine instances, and obtainingthe memory layouts from the other virtual machine instances. Because theexecution context used to generate the memory layouts is decoupled fromthe local execution context of the computer system used to generate thememory layouts, memory layouts may be generated for a variety ofexecution contexts without requiring recompiling or reloading of thesoftware program and/or using different local execution contexts (e.g.,computer hardware and/or platforms) to generate the memory layouts.

In addition, the logical representations, structural representations,and/or memory layouts may be generated from a set of artifactsassociated with executing the software program, such as compiled classesand/or other executable binaries. The set of artifacts may be includedin a package, directory, and/or other type of aggregation or collection.The set of artifacts may be used to determine an inheritance hierarchyassociated with each artifact. The inheritance hierarchy and set ofartifacts may then be used to generate a logical representation of anobject instance represented by the artifact, which in turn may be usedto generate the memory layout of the object instance.

Once the memory layouts are created, visualizations of the memorylayouts may be provided to facilitate understanding of the memorylayouts by a user, such as a developer of the software program. Eachvisualization may include graphical representations of fields and/orother components of the object instances as overlays on a grid, witheach rectangle in the grid representing a unit of memory (e.g., onebyte). As a result, the position and amount of space occupied by agraphical representation may indicate the offset and allocated size ofthe corresponding component. The visualization may also include agraphical distinction between memory space occupied by data in theobject instance and memory space occupied by padding in the objectinstance, as well as a separate graphical distinction among fieldsassociated with different levels of the object instance's inheritancehierarchy. For example, data and padding may be depicted with differentlevels of transparency, while fields may be color-coded according to thelevels of the inheritance hierarchy to which the fields belong.

The structure and/or memory layouts may additionally be used to identifyand/or suggest refactorings of object instances that reduce use ofmemory space in the object instances. First, the structure may beanalyzed to identify portions of the object instances that aredetermined to inefficiently use memory space. For example, the logicalrepresentations may be examined to identify use of multiple Booleans orboxed primitives, fields associated with multiple levels in theinheritance hierarchy, and/or other patterns that may lead toinefficient use of memory in the object instances.

To verify that a portion of an object instance uses memory spaceinefficiently, the memory layout of the object instance in a givenexecution context may be compared to a refactored memory layout of theobject instance, which is generated by applying the same executioncontext to a refactored structure of the object instance. The refactoredstructure may replace a portion of the object instance that isassociated with inefficient use of memory space with a refactoring thatis not associated with inefficient use of memory space. If therefactored memory layout consumes less memory than the original memorylayout, the refactoring associated with the refactored memory layout maybe provided to improve the memory consumption of the object instance. Apotential memory savings associated with the refactoring may also becalculated and provided to further facilitate improved memory usage inthe software program. Finally, a graphical distinction between theportion and the remainder of the object instance's memory space may beincluded in the visualization of the object instance.

FIG. 1 shows a schematic of a system in accordance with the disclosedembodiments. The system may be used to facilitate the development andexecution of a software program 110. Software program 110 may be astandalone application, operating system, enterprise application,database, library, device driver, and/or other type of software. Inaddition, software program 110 may be executed in a variety ofenvironments. For example, software program 110 may be executed on asingle desktop computer or workstation, or software program 110 may bedistributed across multiple servers within a data center. Along the samelines, software program 110 may be executed sequentially or in parallelon one or more processors and/or processor cores.

Software program 110 may also execute independently of the platform ofthe computer system on which software program 110 executes. For example,a virtual machine (e.g., virtual machine instance 104) such as a Java(Java™ is a registered trademark of Oracle America, Inc.) VirtualMachine (JVM) may be used to execute software program 110 on thecomputer system regardless of the operating system, drivers, and/orhardware on the computer system.

More specifically, the system of FIG. 1 may include functionality toimprove memory usage by object instances 112-114 in software program110. Each object instance 112-114 may be an instance of a class and/orother template for creating objects in software program 110. As shown inFIG. 1, the system includes an analysis apparatus 102 and a presentationapparatus 106. Each of these components is described in further detailbelow.

Analysis apparatus 102 may determine a structure of software program110, as well as an execution context 134 for software program 110. Thestructure may include a set of logical representations 116-118 of objectinstances 112-114 and a set of structural representations 136-138generated from logical representations 116-118. Logical representations116-118 may be created from class descriptions of classes in softwareprogram 110, compiled classes, a memory dump of software program 110,and/or other structured representations of classes and/or objectinstances 112-114 in software program 110. Each logical representationmay specify a set of fields in the corresponding object instance, theparent class of the object instance, and/or metadata related to thelayout of the fields in memory. For example, a logical representation ofa Java class may include a set of strings that includes the class nameof the Java class, the name of the Java class's super class, a ContendedAnnotation group name, and/or a set of tuples describing fields (e.g.,field name, data type, Contended Annotation group name) in the class.

In one or more embodiments, logical representations 116-118 are createdfrom a set of artifacts associated with executing software program 110.Each artifact may include compiled and/or executable code for softwareprogram 110. For example, each artifact may be a compiled class insoftware program 110. The set of artifacts may be obtained as a package,directory, and/or other aggregation or collection. For example, a usersuch as a developer of software program 110 may provide a class pathcontaining one or more directories and/or Java packages from which theset of artifacts may be obtained. Analysis apparatus 102 may obtain aset of Java class files from the directories and/or packages and createa logical representation from each class file. Creation of logicalrepresentations of object instances from sets of artifacts is describedin further detail below with respect to FIG. 2.

Execution context 134 may represent a software and/or hardwareenvironment in which software program 110 may be executed. For example,execution context 134 may include a platform, architecture, and/or oneor more configuration options for executing software program 110 withina virtual machine such as a JVM. The platform may include the platformof the execution environment of software program 110, such as a JavaDevelopment Kit (JDK) platform. The architecture may specify thehardware architecture of the computer system on which software program110 may execute, such as a 32-bit architecture and/or 64-bitarchitecture. The configuration options may affect the operation of theexecution environment and the layout of software program 110 in memory.As a result, the configuration options may include options forcompressing object references, enabling or disabling field isolation(e.g., through Java @Contended annotations), padding widths associatedwith field isolation, and/or layout styles or groupings of fields inobject instances 112-114.

Execution context 134 may be a local execution context, which may be anative execution contest of a computer system on which analysisapparatus 102 runs. Alternatively, execution context 134 may be anon-local execution context that differs in hardware and/or softwareconfiguration from that of the local execution context. For example, auser may provide the platform, architecture, and/or configurationoptions associated with a non-local execution context 134 using acommand entered in a command-line interface (CLI) and/or one or moreparameters entered through a graphical user interface (GUI).Alternatively, analysis apparatus 102 may be configured to obtainexecution context 134 as the local execution context and/or an executioncontext found in a memory dump of software program 110.

Logical representations 116-118 may be converted into structuralrepresentations 136-138 using execution context 134. Each structuralrepresentation may be a binary and/or other physical representation ofthe corresponding object instance. For example, a structuralrepresentation of a Java class may include standardized Java byte codethat represents the components listed in the corresponding logicalrepresentation. A JVM instance (e.g., virtual machine instance 104) maybe used to convert the logical representation into a Java binary classthat is used to size the corresponding object instance. In other words,structural representations 136-138 may include information that can beused to determine the layout of the corresponding object instances112-114 in memory.

After the structure of software program 110 and execution context 134are determined, analysis apparatus 102 may use the structure andexecution context 134 to generate memory layouts 120-122 for objectinstances 112-114 in software program 110. In particular, analysisapparatus 102 may apply execution context 134 to structuralrepresentations 136-138 independently of the local execution context ofthe computer system on which analysis apparatus 102 executes. Todecouple creation of memory layouts 120-122 from the local executioncontext, analysis apparatus 102 may configure a virtual machine instance104 to operate within execution context 134 and provide logicalrepresentations 116-118 to virtual machine instance 104. Virtual machineinstance 104 may compute a memory layout (e.g., memory layouts 120-122)for each structural representation, and analysis apparatus 102 mayobtain the memory layout from virtual machine instance 104.

For example, analysis apparatus 102 may instantiate a JVM instance as aremote process and include execution context 134 as one or moreparameters during instantiation of the remote process. Once structuralrepresentations 136-138 are created, analysis apparatus 102 may sendstructural representations 136-138 to the remote process, and the remoteprocess may compute each memory layout 120-122 by calculating offsetsand allocated sizes of fields in the corresponding structuralrepresentations 136-138. The remote process may then provide thecomputed memory layout via an asynchronous notification to analysisapparatus 102.

Alternatively, execution context 134 may be obtained as a localexecution context from a local JVM used by analysis apparatus 102. As aresult, analysis apparatus 102 may use the local JVM to calculate memorylayouts 120-122 in lieu of instantiating a remote JVM with the sameexecution context as the local JVM and using the remote JVM to creatememory layouts 120-122.

In another example, execution context 134 may be provided to an emulatorthat emulates the hardware and/or software used to execute softwareprogram 110. The emulator may generate memory layouts 120-122 by runningsoftware program 110 in a variety of emulated execution contexts (e.g.,execution context 134) and/or applying the emulated execution contextsto structural representations 136-138.

The decoupling of execution context 134 from the local execution contextmay further allow memory layouts 120-122 to be created and comparedacross multiple execution contexts. For example, the user may provide anupdate to execution context 134 to enable the comparison of memorylayouts 120-122 across two or more hardware architectures, includingnon-existent hardware architectures (e.g., a 96-bit architecture). Eachtime execution context 134 is updated or changed, analysis apparatus 102may configure a new virtual machine instance 104 to operate withinexecution context 134 and terminate any previously running virtualmachine instances. Analysis apparatus 102 may then use the newly createdvirtual machine instance to generate memory layouts 120-122 fromstructural representations 136-138. The application of an updatedexecution context by the newly created virtual machine instance mayresult in the creation of memory layouts 120-122 that differ from memorylayouts 120-122 that were previously generated by older virtual machineinstances that operated within older execution contexts.

After memory layouts 120-122 are generated, presentation apparatus 106may display visualizations 124-126 of memory layouts 120-122. Forexample, presentation apparatus 106 may provide visualizations 124-126within the same GUI used to obtain execution context 134 and/or the setof artifacts from which memory layouts 120-122 were generated. Eachvisualization may include a graphical representation of an objectinstance in memory. For example, the memory space of the object instancemay be represented by a grid of rectangles, with each rectanglerepresenting a unit of memory (e.g., one byte). Fields in the objectinstance may be represented by shaded, colored, and/or texturedrectangles in the grid.

The visualization may also include a graphical distinction betweenmemory space occupied by data in the object instance and memory spaceoccupied by padding in the object instance, as well as a differentgraphical distinction between fields associated with different levels ofthe object instance's inheritance hierarchy. For example, padding anddata in the memory space may have different levels of transparency,while fields in the memory space may be color-coded according to theclasses in the inheritance hierarchy of the object instance to which thefields belong. Visualizations of memory layouts in software programs arediscussed in further detail below with respect to FIGS. 4A-4D.

Analysis apparatus 102 and/or presentation apparatus 106 may alsoprovide one or more metrics 128-130 associated with the memory layout ofeach object instance. For example, analysis apparatus 102 may calculatemetrics 128-130 from the artifacts, logical representations 116-118,structural representations 136-138, and/or memory layouts 120-122associated with object instances 112-114. The metrics may include thenumber of references to the object instance, the overall memory usage ofthe object instance, and/or a padding size of the object instance.Presentation apparatus 106 may display metrics 128-130 next tovisualizations 124-126 to facilitate user understanding of the memoryusage of object instances 112-114. Calculation of metrics associatedwith memory layouts of object instances is described in further detailbelow with respect to FIG. 2.

Analysis apparatus 102 and presentation apparatus 106 may furtherimprove the memory usage of software program 110 by identifying portionsof object instances 112-114 that inefficiently use memory space insoftware program 110. For example, analysis apparatus 102 may examinelogical representations 116-118 to identify use of multiple Booleans orboxed primitives, multiple levels in the inheritance hierarchy, and/orother patterns that may lead to inefficient use of memory in objectinstances 112-114.

To verify that a portion of an object instance uses memory spaceinefficiently within a given execution context 134, analysis apparatus102 may compare the memory layout of the object instance to a refactoredmemory layout of the object instance, which is generated by applying thesame execution context 134 to a refactored structure of the objectinstance. The refactored structure may replace a portion of the objectinstance that is associated with inefficient use of memory space with arefactoring that is not associated with inefficient use of memory space.If the refactored memory layout consumes less memory than the originalmemory layout, presentation apparatus 106 may provide the refactoring toimprove the memory consumption of the object instance. Analysisapparatus 102 may further calculate a potential memory savingsassociated with the refactoring, and presentation apparatus 106 mayinclude the potential memory savings in the set of metrics associatedwith the object instance. Finally, presentation apparatus 106 maydisplay a graphical distinction between the portion and the remainder ofthe object instance's memory space in the visualization of the objectinstance.

Those skilled in the art will appreciate that the system of FIG. 1 maybe implemented in a variety of ways. First, analysis apparatus 102,virtual machine instance 104, and presentation apparatus 106 may beprovided by a single physical machine, multiple computer systems, one ormore virtual machines (e.g., JVMs), a grid, and/or a cloud computingsystem. For example, the same virtual machine instance (e.g., virtualmachine instance 104) or different virtual machine instances may be usedto generate structural representations 136-138 from logicalrepresentations 116-118 and memory layouts 120-122 from structuralrepresentations 136-138. In addition, analysis apparatus 102 andpresentation apparatus 106 may be implemented together and/or separatelyby one or more hardware and/or software components and/or layers.

Second, analysis apparatus 102 and presentation apparatus 106 may beconfigured to provide memory layouts 120-122, visualizations 124-126,and/or metrics 128-130 for a variety of development and/or executionenvironments. As mentioned above, analysis apparatus 102 and virtualmachine instance 104 may enable the generation of memory layouts 120-122associated with a number of possible execution contexts, independentlyof the local execution context of the computer system on which analysisapparatus 102 runs. The execution contexts may also includenon-virtualized execution contexts, such as native execution of softwareprogram 110 on a given platform, operating system, and/or set ofhardware instead of a virtual machine. Along the same lines, analysisapparatus 102 and presentation apparatus 106 may be configured toprovide memory layouts 120-122, visualizations 124-126, and/or metrics128-130 for software programs developed using a variety of programminglanguages and/or software development kits (SDKs).

FIG. 2 shows the generation of a memory layout 218 of an object instancein a software program (e.g., software program 110 of FIG. 1) inaccordance with the disclosed embodiments. As shown in FIG. 2, memorylayout 218 may be created from a set 202 of artifacts 204-206 associatedwith executing the software program. Artifacts 204-206 may includecompiled classes and/or other binary or executable forms of the softwareprogram. Alternatively, artifacts 204-206 may be obtained from a memorydump of the software program, structured descriptions of classes in thesoftware program, and/or other representations of the classes.

Set 202 may be obtained as a directory, library, package, and/or othercollection or aggregation of artifacts 204-206. For example, set 202 mayinclude all the compiled classes required to execute the softwareprogram, or set 202 may include artifacts 204-206 that are used toimplement or execute an individual component or module of the softwareprogram.

More specifically, set 202 may include an artifact that represents theobject instance. To create memory layout 218 for the object instance, aset of superclass declarations 208 may be obtained from artifacts204-206 and used to identify an inheritance hierarchy 210 associatedwith the artifact. For example, one or more artifacts 204-206 may have asuperclass declaration that specifies a superclass of the artifact. As aresult, a chain of superclass declarations from the artifact to thetopmost superclass of the inheritance hierarchy may be used to identifythe classes that make up different levels of inheritance hierarchy 210.If a superclass declaration in the chain cannot be resolved to aparticular artifact in set 202 (e.g., because the artifact is not in set202), building of memory layout 218 may fail.

Next, inheritance hierarchy 210 may be used to obtain a set of fielddeclarations 212 and metadata 214 from the artifact and additionalartifacts in inheritance hierarchy 210. Field declarations 212 mayinclude named values and types of fields in the artifacts. For example,field declarations 212 may include variable declarations, which specifythe names and types of variables used by the artifacts. Metadata 214 maybe related to the layout of the object instance in memory. For example,metadata 214 for a Java object may include the @Contended annotation,which adds padding before and after a field to isolate the field inmemory.

Field declarations 212 and metadata 214 are then used to create alogical representation 216 of the object instance. As described above,logical representation 216 may include the order in which the fieldswere declared in field declarations 212, the levels of inheritancehierarchy 210 to which the fields belong, and/or one or more arraysincluded in the fields. Logical representation 216 may also includemetadata 214 and/or other attributes that may affect the placement ofthe fields in memory layout 218, such as a hierarchy of Java Contentiongroups associated with the fields.

Logical representation 216 may be converted into a structuralrepresentation 224 of the object instance, such as a standardized binaryversion of the object instance that can be used to size the fieldsand/or components of the object instance. A virtual machine instance 104may then apply execution context 134 to structural representation 224 togenerate memory layout 218. As mentioned above, virtual machine instance104 may be configured to operate within execution context 134. Forexample, virtual machine instance 104 may be instantiated as a remoteprocess using a platform (e.g., platform version), architecture (e.g.,hardware architecture), and/or one or more configuration options(compression options, padding options, layout options, etc.). If achange to execution context 134 is made, a new virtual machine instancemay be instantiated using the change, and virtual machine instance 104may be terminated.

Once structural representation 224 is provided to virtual machineinstance 104, virtual machine instance 104 may generate memory layout218 by determining the allocated sizes and offsets of fields and/orother components in structural representation 224. In addition, memorylayout 218 may be affected by execution context 134. For example,virtual machine instance 104 may generate a more efficient memory layout218 with a 64-bit architecture in execution context 134 than with a32-bit architecture in execution context 134, because the larger wordsize of the 64-bit architecture may allow for encoding and/or otheroptimizations that improve the memory usage of the object instance.

In one or more embodiments, memory layout 218 includes a set ofcomponents in the object instance, as computed by virtual machineinstance 104. For example, memory layout 218 may include a headercomponent occupying the first word of memory layout 218, followed by ametadata component that references metadata for the class and/or entityrepresented by the object instance. Memory layout 218 may also include anumber of additional components, such as an array component describingthe length of an array, a contention padding component specifyingpadding caused by the Java @Contended annotation, and/or an externalpadding component specifying padding at the end of memory layout 218(e.g., due to data alignment requirements associated with executioncontext 134). The components may further include a field componentspecifying the layout of a field in the object instance, a split fieldcomponent indicating that a field is longer than the word size (e.g., adouble or long in 32-bit architecture), and/or an internal paddingcomponent specifying padding inserted within memory layout 218.

Memory layout 218 may also include the names, types, offsets, andallocated sizes of the components, as well as the levels of inheritancehierarchy 210 to which the components belong. For example, memory layout218 may specify a field element with a name of “myinteger,” a type of“int,” an offset of 12, and a size of 4. Memory layout 218 may alsoindicate that the field element belongs to (e.g., is owned by) a classin inheritance hierarchy 210 that is two levels above the objectinstance (e.g., the superclass of the superclass of the objectinstance).

Once memory layout 218 is created, a visualization 222 of memory layout218 may be provided. Visualization 222 may include components in memorylayout 218 as overlays on a grid. As described in further detail belowwith respect to FIGS. 4A-4D, visualization 222 may distinguish betweendata and padding in memory layout 218, as well as fields associated withdifferent levels of inheritance hierarchy in memory layout 218.

A set of metrics 220 associated with memory layout 218 may additionallybe determined and provided along with visualization 222. For example,metrics 220 may include the allocated sizes and offsets of components inmemory layout 218, the overall memory usage of the object instance, theamount of padding in the object instance, and/or the number ofreferences to the object instance (e.g., as an estimate of the number oftimes the object instance recurs in the software program). Metrics 220may be displayed within the same GUI as visualization 222, as describedbelow with respect to FIGS. 4A-4D. Finally, metrics 220 may include apotential memory savings associated with refactoring of the objectinstance, the calculation of which is described below with respect toFIG. 3.

FIG. 3 shows the identification of an improvement to the memory usage ofa software program in accordance with the disclosed embodiments. Morespecifically, FIG. 3 shows the identification of an improvement in thememory usage of an object instance in the software program based on arefactoring 306 of the object instance. First, a structure 302 of theobject instance is obtained. As discussed above, structure 302 mayinclude information that can be used to generate a memory layout 310 ofthe object instance based on execution context 134. For example,structure 302 may be described in a structural (e.g., binary)representation of the object instance, which is created from a logicalrepresentation of the object instance.

Next, structure 302 may be analyzed to identify a portion 304 of theobject instance that may be associated with inefficient use of memoryspace 318 in the software program. Such inefficient use of memory spacemay be caused by the use of data structures or types that can bereplaced by other data structures or types that achieve the samebehavior with a smaller memory footprint. For example, structure 302 maybe analyzed to identify patterns that may lead to inefficient use ofmemory in the object instance. Such patterns may include, but are notlimited to, a large number of Booleans in the object instance that canbe replaced by a bit set that consumes less memory, a large number oflevels in the inheritance hierarchy of the object instance that resultsin padding in between fields of different levels of the inheritancehierarchy, and/or use of boxed primitives that occupy more memory thansimple primitives. Portions that match the patterns, including portion304, may be flagged for subsequent analysis.

In the subsequent analysis, a refactoring 306 of the object instance maybe used to generate a refactored structure 308 of the object instance.Refactoring 306 may include a variation of portion 304 that does notinclude a pattern associated with inefficient use of memory space 318.For example, refactoring 306 may replace a set of Booleans in portion304 with a bit set that consumes less memory, reduce the number oflevels in the inheritance hierarchy associated with fields in portion304, reorder fields in portion 304, and/or replace boxed primitives inportion 304 with simple primitives. In turn, structure 308 may include astructure that reflects refactoring 306 of portion 304 in the objectinstance.

Memory layout 310 may be generated from structure 302 and executioncontext 134, and a refactored memory layout 312 may be generated fromrefactored structure 308 and the same execution context 134. Memoryconsumptions 314-316 of memory layout 310 and refactored memory layout312 may also be calculated by, for example, adding the allocated sizesof all components in each memory layout, including padding components.Memory consumption 314 of memory layout 310 may then be compared withmemory consumption 316 of refactored memory layout 312 to determine ifinefficient use of memory space 318 is present in the object instance.For example, the object instance may be determined to inefficiently usememory space if memory consumption 316 is lower than memory consumption314.

Once inefficient use of memory space 318 in the object instance isestablished, a potential memory savings 320 associated with refactoring306 is calculated. For example, potential memory savings 320 may becalculated as the difference in memory consumption 314-316 betweenmemory layout 310 and refactored memory layout 312. Potential memorysavings 320 may also be calculated based on a number of references 322to the object instance in the software program. For example, thedifference in memory consumption 314-316 may be multiplied by number ofreferences 322 to obtain an overall potential memory savings 320associated with refactoring 306 of the object instance across thesoftware program.

To enable improved memory usage in the software program, refactoring 306may be provided to the user in a user interface such as a GUI and/orCLI. Similarly, a visualization 324 of memory layout 310 may bedisplayed within the same user interface, and portion 304 may bedistinguished from other components in memory layout 310 invisualization 324, as discussed in further detail below with respect toFIG. 4B. Finally, the object instance may be included in a ranking 326of object instances in the software program by potential memory savings320. For example, potential memory savings 320 may be calculated for allobject instances that are determined to inefficiently use memory space,and the object instances may be included in ranking 326 by descendingorder of potential memory savings 320 to facilitate larger reductions inthe memory consumption of the software program, as discussed below withrespect to FIG. 4D.

FIG. 4A shows an exemplary screenshot in accordance with the disclosedembodiments. More specifically, FIG. 4A shows a screenshot of a userinterface provided by a presentation apparatus, such as presentationapparatus 106 of FIG. 1. For example, the presentation apparatus mayform part of a tool that is used to view, manage, and/or improve thememory consumption of a software program, such as software program 110of FIG. 1

As shown in FIG. 4A, the user interface includes a visualization 402 ofa memory layout of an object instance in the software program.Visualization 402 may include a grid of rectangles and a set ofcomponents 406-422 overlaid on the grid. Each rectangle in the grid mayrepresent a unit of memory, such as one byte. In addition, each row ofvisualization 402 may be labeled with a memory offset; the first row maystart at offset 0, the second row may start at offset 8, the third rowmay start at offset 16, the fourth row may start at offset 24, and thefifth row may start at offset 32.

Components 406-422 may be positioned in the grid based on the offsetsand allocated sizes of components 406-422, which may be obtained fromthe memory layout of the object instance. For example, the memory layoutmay specify a first component 406 with an offset of 0 and a size of 8, asecond component 408 with an offset of 8 and a size of 4, a thirdcomponent 410 with an offset of 12 and a size of 4, a fourth component412 with an offset of 16 and a size of 4, and a fifth component 414 withan offset of 20 and a size of 4. The memory layout may also include asixth component 416 with an offset of 24 and a size of 8, a seventhcomponent 418 with an offset of 32 and a size of 1, an eighth component420 with an offset of 33 and a size of 1, and a ninth component 422 withan offset of 34 and a size of 6.

Characteristics of components 406-422 from the memory layout may also bereflected in the appearance of components 406-422 in visualization 402.First, the borders of components 406-408 and 416-422 may be shown in afirst color (e.g., beige), the borders of components 412-414 may beshown in a second color (e.g., purple), and the border of component 410may be shown in a third color (e.g., green). Such color-coding ofcomponents 406-422 may represent ownership of components 406-422 bydifferent levels of the object instance's inheritance hierarchy. Forexample, the first (e.g., beige) color may indicate ownership ofcomponents 406-408 and 416-422 by the base class from which the objectinstance is created, the second (e.g., purple) color may indicateownership of components 412-414 by a superclass of the base class, andthe third (e.g., green) color may represent ownership of component 410by a superclass of the superclass.

Second, components 406-420 may be opaque, while component 422 may besemi-transparent. The difference in transparency between components406-420 and component 422 may be used to distinguish between data in theobject instance and padding in the object instance. For example, theopacity of components 406-420 may indicate that components 406-420represent fields and/or other data in the object instance, while thesemi-transparency of component 422 may indicate that component 422 ispadding in the object instance's memory layout.

The user interface of FIG. 4A also includes a table 404 of informationrelated to components 406-422 in visualization 402. Each row 424-440 intable 404 may include data for a given component 406-422 invisualization 402. For example, table 404 may provide offsets, allocatedsizes, names, types, and/or owners of components 406-422. Row 424 maydescribe an offset of 0, a size of 8, a name of “Mark” (e.g., markword), and an owner of “com.my.class” for component 406. Row 426 mayspecify an offset of 8, a size of 4, a name of “Metadata” (e.g., classmetadata), and the same owner of “com.my.class” for component 408.Components 406-408 may be owned by the “com.my.class” class (e.g., thebase class from which the object instance is created) because components406-408 would not be present if the base class did not exist.

Row 428 may include an offset of 12, a size of 4, a name of “i1,” a typeof “int,” and an owner of “com.my.super2” for component 410. Row 428 mayindicate that the component 410 belongs to a different class (e.g., asuper-superclass) than the base class from which the object instance iscreated, which is reflected in the green coloring of component 410 invisualization 402.

Row 430 may provide an offset of 16, a size of 4, a name of “i2,” a typeof “int,” and an owner of “com.my.super1” for component 412. Row 432 mayinclude an offset of 20, a size of 4, a name of “s1,” a type of“String,” and an owner of “com.my.super1” for component 414. Rows430-432 may indicate that components 412-414 belong to a different classthan the classes that own components 406-410 (e.g., a superclass of thebase class), which is reflected in the purple coloring of components412-414 in visualization 402.

Row 434 may specify an offset of 24, a size of 8, a name of “11,” a typeof “long,” and an owner of “com.my.class” for component 416. Row 436 mayinclude an offset of 32, a size of 1, a name of “b1,” a type of“boolean,” and an owner of “com.my.class” for component 418. Row 438 mayinclude an offset of 33, a size of 1, a name of “b2,” a type of“boolean,” and an owner of “com.my.class” for component 420. Rows434-438 may indicate that components 416-420 are owned by the same classas components 406-408, which is shown in the beige coloring ofcomponents 406-408 and 416-420.

Finally, row 440 may specify an offset of 34, a size of 6, a name of“<padding>,” and an owner of “com.my.class” for component 422. Row 440may indicate that component 422 is padding that is appended to the endof the object instance to meet data alignment requirements associatedwith the layout of object instances in memory. Component 422 is giventhe same owner as components 418-420 because component 422 would notexist if components 418-420 were not located in their respectivepositions in the object instance's memory layout.

FIG. 4B shows an exemplary screenshot in accordance with the disclosedembodiments. Like the screenshot of FIG. 4A, FIG. 4B shows a screenshotof a user interface provided by a presentation apparatus, such aspresentation apparatus 106 of FIG. 1.

The user interface of FIG. 4B also includes a visualization 442 of amemory layout of an object instance. Within visualization 442, a numberof components 444-466 in the object instance are overlaid on rectanglesof a grid. Rows of the grid may represent memory offsets of 0 to 40.Component 444 may have an offset of 0 and a size of 8, component 446 mayhave an offset of 8 and a size of 4, component 448 may have an offset of12 and a size of 4, component 450 may have an offset of 16 and a size of4, and component 452 may have an offset of 20 and a size of 4. Component454 may have an offset of 24 and a size of 4, component 456 may have anoffset of 28 and a size of 2, and components 458-464 may all have a sizeof 1 and offsets of 30, 31, 32, and 33, respectively. Finally, component466 may have an offset of 34 and a size of 6.

Components 444-466 may also have distinct coloring, transparency, and/orother graphical distinctions. For example, the borders of components444-466 may be colored beige, purple, or green to indicate ownership ofcomponents 444-466 by a base class, a superclass of the base class,and/or a superclass of the superclass. Similarly, component 466 may bemore transparent than components 444-464 to indicate that component 466represents padding in the object instance and components 444-464represent data in the object instance.

Moreover, the center of components 458-464 may be colored yellow, whilethe center of other components 444-456 and 466 may be colored gray. Theyellow coloring of components 458-464 may identify a portion of theobject instance that is determined to inefficiently use memory space inthe software program. For example, components 458-464 may represent fourBoolean fields that cause a padding component 466 to be included in thememory layout. By flagging components 458-464 in visualization 442, theuser interface may allow a user (e.g., a developer of the softwareprogram) to refactor the corresponding fields and reduce the memoryusage of the software program. For example, the user may usevisualization 442 to identify the four Boolean fields represented bycomponents 458-464 and refactor the fields into a bit set that fits intothe 31^(st) byte of the memory layout, thus reducing the overall memoryconsumption of the object instance by 8 bytes. Visualization 442 mayalso be accompanied by a suggestion for refactoring the object instance,as described below with respect to FIG. 4D.

FIG. 4C shows an exemplary screenshot in accordance with the disclosedembodiments. As with the screenshots of FIGS. 4A-4B, FIG. 4C shows ascreenshot of a user interface provided by a presentation apparatus,such as presentation apparatus 106 of FIG. 1. In particular, the userinterface of FIG. 4C includes a table 468 of data related to memoryconsumption of object instances in a software program. Table 468 may beshown next to a visualization of a memory layout of an object instancein the software program, or table 468 may be shown on a separate screenof the user interface.

Each row 470-482 in table 468 may include a size, a padding size, and aclass name of an object instance in the software program. Row 470 has asize of 376, a padding size of 257, and a class name of“com.my.bigclass.” Row 472 has a size of 80, a padding size of 10, and aclass name of “com.my.bigclass2.” Row 474 has a size of 72, a paddingsize of 7, and a class name of “com.my.super2.” Row 476 has a size of56, a padding size of 8, and a class name of “com.my.super1.” Row 478has a size of 48, a padding size of 4, and a class name of“com.my.class3.” Row 480 has a size of 48, a padding size of 6, and aclass name of “com.my.class2.” Row 482 has a size of 40, a padding of 6,and a class name of “com.my.class,” which represents the class fromwhich the object instance of FIG. 4A is created.

In addition, rows 470-482 may be sorted in decreasing order of size.Such sorting may allow a user to identify object instances that uselarge amounts of memory in the software program. The user may select aheader (e.g., “Size,” “Padding,” “Class”) in table 468 to sort data inrows 470-482 by the attribute represented by the header. For example,the user may click on the “Padding” header to sort data in rows 470-482by decreasing order of padding size to identify object instances withthe most padding (e.g., wasted memory) in the software program.Alternatively, the user may click on the “Class” header to sort data inrows 470-482 by alphabetical order of class name to locate an objectinstance with a given class name in table 468.

FIG. 4D shows an exemplary screenshot in accordance with the disclosedembodiments. As with the screenshots of FIGS. 4A-4C, FIG. 4D shows ascreenshot of a user interface provided by a presentation apparatus,such as presentation apparatus 106 of FIG. 1. The user interface of FIG.4D includes a table 484 of data related to memory consumption of objectinstances in a software program. As with table 468 of FIG. 4C, table 484may be shown next to a visualization of a memory layout of an objectinstance in the software program or on a different screen of the userinterface.

Unlike table 468, each row 486-492 of table 484 may include a potentialgain (e.g., potential memory savings) associated with refactoring of anobject instance in the software program, followed by the class name ofthe object instance. Row 486 has a potential gain of 24 and a class nameof “com.my.class4,” row 488 has a potential gain of 16 and a class nameof “com.my.class2,” row 490 has a potential gain of 8 and a class nameof “com.my.class,” and row 492 has a potential gain of 8 and a classname of “com.my.class3.”

The user interface also includes a label 494 (e.g., “Classes that couldbenefit from boolean refactoring”) that identifies the type ofrefactoring to be performed to obtain the memory gains in table 484. Forexample, label 494 may indicate that the object instances associatedwith rows 486-492 may be refactored by converting Boolean fields in theobject instances into bit sets that occupy less memory. In turn, therefactoring of each object instance may eliminate padding at the end ofthe object instance's memory layout, thus providing a potential memorysavings of a multiple of 8. Differences in the potential memory savingsof the object instances may be due to the number and/or positions ofBoolean fields to be refactored in each object instance. Alternatively,the potential memory savings shown in table 484 may be based on thenumber of references to a given object instance. For example, apotential memory savings of 16 for an object instance may be based on arefactoring of the object instance that reduces the memory consumptionof the object instance by 16 bytes or a refactoring that reduces memoryconsumption by 8 bytes multiplied by two references to the objectinstance in the software program.

FIG. 5 shows a flowchart illustrating the process of facilitating theexecution of a software program in accordance with the disclosedembodiments. In one or more embodiments, one or more of the steps may beomitted, repeated, and/or performed in a different order. Accordingly,the specific arrangement of steps shown in FIG. 5 should not beconstrued as limiting the scope of the embodiments.

Initially, a memory layout for an object instance in the softwareprogram is obtained (operation 502). The memory layout may include a setof offsets and a set of allocated sizes of a set of componentsassociated with the object instance. The memory layout may be generatedbased on a structure and an execution context for the software program,as described below with respect to FIG. 6. The memory layout may begenerated using a logical representation of the object instance and avirtual machine instance, as described below with respect to FIG. 7. Thememory layout may further be generated from a set of artifactsassociated with executing the software program, as described in furtherdetail below with respect to FIGS. 8-9.

Next, the memory layout is used to determine a first memory spaceoccupied by data in the object instance and a second memory spaceoccupied by padding in the object instance (operation 504). For example,the memory layout may be examined to obtain the offsets and allocatedsizes of one or more fields in the object instance, as well as theoffsets and allocated sizes of one or more padding components in theobject instance.

Similarly, the memory layout is used to determine a first fieldassociated with a first level of an inheritance hierarchy of the objectinstance and a second field associated with a second level of theinheritance hierarchy (operation 506). For example, the memory layoutmay specify the owner (e.g., base class, superclass, super-superclass,etc.) of each field in the object instance, which may allow the level ofthe inheritance hierarchy associated with the field to be determined.

A visualization of the memory layout is then displayed (operation 508).The visualization may include a graphical distinction between the firstand second memory spaces, as well as a different graphical distinctionbetween the first and second fields. For example, the graphicaldistinctions may include differences in the color, transparency,shading, texture, shape, and/or other visual attributes of components inthe visualization. The visualization may thus facilitate userunderstanding of the layout and ordering of components in the objectinstance, as well as identification of components associated with memorywaste (e.g., padding) in the object instance.

A memory consumption and padding size of the object instance is alsodisplayed (operation 510). For example, the memory consumption and/orpadding size may be included in a list of object instances that isordered by decreasing memory consumption and/or padding size. As aresult, the memory consumption and/or padding size may allow a user tocompare the memory usage and/or waste of the object instance with thoseof other object instances in the software program.

FIG. 6 shows a flowchart illustrating the process of facilitating theexecution of a software program in accordance with the disclosedembodiments. In one or more embodiments, one or more of the steps may beomitted, repeated, and/or performed in a different order. Accordingly,the specific arrangement of steps shown in FIG. 6 should not beconstrued as limiting the scope of the embodiments.

First, the structure of the software program is determined (operation602). The structure of the software program may include information thatcan be used to generate memory layouts of object instances in thesoftware program, as described in further detail below with respect toFIG. 7. An execution context for the software program is also determinedfrom a set of possible execution contexts (operation 604). For example,the execution context may be obtained from a local execution context, amemory dump of the software program, and/or user input.

Memory layouts for a set of object instances in the software program aregenerated by applying the execution context to the structureindependently of a local execution context (operation 606) of a computersystem used to generate the memory layouts. For example, the memorylayouts may be generated using a virtual machine instance that isconfigured to operate within the execution context, as discussed belowwith respect to FIG. 7.

The memory layouts are then stored in association with the softwareprogram (operation 608). For example, the memory layouts may be storedin a database and/or filesystem for subsequent retrieval and/or use ingenerating visualizations of the memory layouts.

The execution context may be updated (operation 610). For example, theexecution context may be updated to enable the generation of memorylayouts within different execution contexts. If the execution context isupdated, the updated execution context is determined from the set ofpossible execution contexts (operation 604), and memory layouts for theobject instances are generated and stored (operation 606-608) based onthe updated execution context. Such context-based generation of memorylayouts may continue until memory layouts have been generated and storedfor all relevant execution contexts (e.g., a set of execution contextsacross which the memory layouts are to be compared).

FIG. 7 shows a flowchart illustrating the process of generating memorylayouts for a set of object instances in a software program inaccordance with the disclosed embodiments. In one or more embodiments,one or more of the steps may be omitted, repeated, and/or performed in adifferent order. Accordingly, the specific arrangement of steps shown inFIG. 7 should not be construed as limiting the scope of the embodiments.

Initially, a set of logical representations associated with the objectinstances is created (operation 702). Each logical representation mayinclude a set of fields, a parent class, and/or metadata related to alayout of the fields. As a result, the logical representations mayrepresent the structure of the software program. Creation of logicalrepresentations of object instances is described below with respect toFIG. 8.

Next, the logical representations are converted into a set of structuralrepresentations of the object instances (operation 704). For example,each logical representation may include a set of strings describing thefields, parent class, and/or metadata related to the layout of thefields in the corresponding object instance. Each component (e.g.,field, parent class, metadata) listed in the logical representation maybe converted into a binary version of the same component (e.g., instancefield, parent structural representation, contention group hierarchy,etc.) in the corresponding structural representation.

Next, a virtual machine instance is configured to operate within anexecution context (operation 706). For example, the virtual machineinstance may be instantiated to operate with a given platform,architecture, and/or set of configuration options, as provided by auser, local execution context, and/or memory dump of the softwareprogram. If the execution context is the local execution context, alocal virtual machine instance may be used. If the execution contextdiffers from the local execution context, a remote virtual machineinstance may be instantiated to operate within the execution context. Ifthe execution context is updated, a new virtual machine instance may beinstantiated to operate within the updated execution context, and anypreviously executing virtual machine instances may be terminated.

The set of structural representations is then provided to the virtualmachine instance (operation 708) and used by the virtual machineinstance to generate the memory layouts. The memory layouts are thenobtained from the virtual machine instance (operation 710). For example,a communication protocol may be used to transmit the logicalrepresentations to a remote virtual machine instance and receive memorylayouts from the virtual machine instance.

FIG. 8 shows a flowchart illustrating the process of generating memorylayouts for object instances in a software program in accordance withthe disclosed embodiments. In one or more embodiments, one or more ofthe steps may be omitted, repeated, and/or performed in a differentorder. Accordingly, the specific arrangement of steps shown in FIG. 8should not be construed as limiting the scope of the embodiments.

First, a set of artifacts associated with executing the software programis obtained (operation 802). The set of artifacts may include compiledclasses and/or other structured representations of classes. Theartifacts may be obtained as a package, directory, and/or otheraggregation or collection. For example, a user may specify one or morepackages and/or directories containing the set of artifacts.

Next, the set of artifacts is used to determine an inheritance hierarchyassociated with an artifact from the set (operation 804). Theinheritance hierarchy of the artifact may be identified from superclassdeclarations in the artifact and one or more additional artifactsassociated with the inheritance hierarchy. For example, the inheritancehierarchy may be determined by following a chain of superclassdeclarations from the artifact to one or more additional artifacts untilthe top of the inheritance hierarchy is reached.

Once the inheritance hierarchy is determined, the inheritance hierarchyand set of artifacts are used to generate a memory layout of an objectinstance represented by the artifact (operation 806). To generate thememory layout, a logical representation of the object instance iscreated, as described below with respect to FIG. 9. The logicalrepresentation may then be provided to a virtual machine instance, andthe memory layout may be obtained from the virtual machine instance, asdiscussed above.

The set of artifacts may also be used to determine one or more metricsassociated with the memory layout (operation 808). For example, the setof artifacts may be examined to determine the number of references tothe object instance, the overall memory usage associated with the objectinstance, and/or a potential memory savings associated with the objectinstance. Calculation and use of potential memory savings associatedwith object instances is described below with respect to FIGS. 10-11.

Additional memory layouts may be generated (operation 810) from the setof artifacts. For example, memory layouts may be generated for some orall of the artifacts in the set. If additional memory layouts are to begenerated, the set of artifacts is used to determine the inheritancehierarchy associated with an artifact (operation 804) representing anobject instance for which a memory layout is to be generated, and theinheritance hierarchy and set of artifacts are used to generate thememory layout of the object instance (operation 806). One or moremetrics associated with the memory layout may also be determined(operation 808). Generation of memory layouts from the set of artifacts(operation 810) may thus continue until all memory layouts and/orrelated metrics have been generated from the set of artifacts.

FIG. 9 shows a flowchart illustrating the process of using a set ofartifacts to generate a memory layout of an object instance representedby an artifact from the set of artifacts in accordance with thedisclosed embodiments. In one or more embodiments, one or more of thesteps may be omitted, repeated, and/or performed in a different order.Accordingly, the specific arrangement of steps shown in FIG. 9 shouldnot be construed as limiting the scope of the embodiments.

First, the inheritance hierarchy of an artifact is identified from a setof superclass declarations in the artifact and one or more additionalartifacts associated with the inheritance hierarchy (operation 902). Asmentioned above, the inheritance hierarchy may be determined byfollowing a chain of superclass declarations from the artifact to one ormore additional artifacts until the top of the inheritance hierarchy isreached.

Next, a set of field declarations is obtained from the artifact andadditional artifact(s) (operation 904) and used to generate a logicalrepresentation of the object instance (operation 906). For example, thefield declarations and/or artifacts may be used to add the names, types,and/or owners of the fields to the logical representation. Similarly,metadata related to the memory layout is obtained from the artifact andadditional artifact(s) (operation 908) and included in the logicalrepresentation of the object instance (operation 910). For example,metadata related to the Java @ Contended annotation may be obtained fromthe artifacts and added to the logical representation to facilitateaccurate generation of a memory layout from the logical representation.

Finally, the logical representation is provided to a virtual machineinstance (operation 912), and the logical representation is used by thevirtual machine instance to generate the memory layout. For example, thevirtual machine instance may convert the logical representation into astructural representation of the object instance, and the same virtualmachine or a different virtual machine may generate the memory layoutfrom the structural representation.

FIG. 10 shows a flowchart illustrating the process of improving memoryusage in a software program in accordance with the disclosedembodiments. In one or more embodiments, one or more of the steps may beomitted, repeated, and/or performed in a different order. Accordingly,the specific arrangement of steps shown in FIG. 10 should not beconstrued as limiting the scope of the embodiments.

First, a structure of a software program is determined, along with anexecution context for the software program from a set of possibleexecution contexts (operation 1002). The software program may includeone or more object instances created from one or more classes. Next, thestructure and execution context are used to identify a portion of anobject instance in the software program that is determined toinefficiently use memory space in the software program (operation 1004),as described below with respect to FIG. 11.

A refactoring of the object instance that reduces use of the memoryspace in the object instance is then provided (operation 1006) toimprove the memory usage of the software program. For example, therefactoring may be displayed as a suggestion within a user interface ofa tool for improving the memory usage of the software program. Apotential memory savings associated with refactoring of the objectinstance is also calculated (operation 1008) and provided (operation1010). For example, the potential memory savings may be displayed withinthe same user interface as the refactoring.

The object instance is further included in a ranking of object instancesin the software program by potential memory savings (operation 1012).For example, the object instance may be displayed in a list of objectinstances that is sorted in descending order of potential memorysavings. Finally, a visualization of the memory layout of the objectinstance is displayed (operation 1014). The visualization may include agraphical distinction between the portion that inefficiently uses thememory space and the remainder of the memory space. For example, thegraphical distinction may flag one or more fields in the memory layoutthat cause the memory layout to add extra padding in the memory space.

FIG. 11 shows a flowchart illustrating the process of identifyinginefficient use of memory space in an object instance in a softwareprogram in accordance with the disclosed embodiments. In one or moreembodiments, one or more of the steps may be omitted, repeated, and/orperformed in a different order. Accordingly, the specific arrangement ofsteps shown in FIG. 11 should not be construed as limiting the scope ofthe embodiments.

Initially, a memory layout for the object instance is generated byapplying an execution context for the software program to a structure ofthe software program (operation 1102), as described above. A refactoredmemory layout for the object instance is also generated by applying theexecution context to a refactored structure of the object instance(operation 1104). The refactored structure may replace a portion of theobject instance that matches a pattern associated with inefficient useof memory space with a refactoring that is not known to inefficientlyuse memory space. For example, the refactored structure may have a bitset in place of multiple Boolean fields in the original object instance,simple primitives in lieu of boxed primitives in the original objectinstance, and/or a reordering or reassigning of fields from the originalobject instance.

Next, the object is determined to inefficiently use the memory spacebased on the difference in memory consumption between the memory layoutand the refactored memory layout (operation 1106). For example, theobject may be determined to inefficiently use the memory space if thememory consumption of the refactored memory layout is lower than thememory consumption of the memory layout.

A potential memory savings is then calculated from the difference inmemory consumption between the memory layout and the refactored memorylayout (operation 1108). For example, the potential memory savings maybe calculated by subtracting the memory consumption of the refactoredmemory layout from the memory consumption of the memory layout. Thepotential memory savings may further be calculated by multiplying thedifference in memory consumption by the number of references to theobject instance in the software program (operation 1110). The potentialmemory savings may thus reflect the number of times the object instancerecurs in the software program, resulting in a higher potential memorysavings the more times the object instance recurs in the softwareprogram.

FIG. 12 shows a computer system 1200 in accordance with an embodiment.Computer system 1200 may correspond to an apparatus that includes aprocessor 1202, memory 1204, storage 1206, and/or other components foundin electronic computing devices such as personal computers, laptopcomputers, workstations, servers, mobile phones, tablet computers,and/or portable media players. Processor 1202 may support parallelprocessing and/or multi-threaded operation with other processors incomputer system 1200. Computer system 1200 may also include input/output(I/O) devices such as a keyboard 1208, a mouse 1210, and a display 1212.

Computer system 1200 may include functionality to execute variouscomponents of the present embodiments. In particular, computer system1200 may include an operating system (not shown) that coordinates theuse of hardware and software resources on computer system 1200, as wellas one or more applications that perform specialized tasks for the user.To perform tasks for the user, applications may obtain the use ofhardware resources on computer system 1200 from the operating system, aswell as interact with the user through a hardware and/or softwareframework provided by the operating system.

In one or more embodiments, computer system 1200 provides a system forfacilitating the execution of a software program. The system may includean analysis apparatus that determines a structure of the softwareprogram and an execution context for the software program from a set ofpossible execution contexts for the software program. Next, the analysisapparatus may generate memory layouts for a set of object instances inthe software program by applying the execution context to the structureindependently of a local execution context on computer system 1200. Theanalysis apparatus may use a set of artifacts associated with executingthe software program and/or a set of logical representations of theobject instances to generate the memory layouts and/or determine one ormore metrics associated with each memory layout.

The system may also include a presentation apparatus that obtains thememory layouts and displays visualizations of the memory layouts (e.g.,within a GUI). Each visualization may include graphical distinctionsbetween data in the corresponding object instance and padding in theobject instance, fields associated with different levels of aninheritance hierarchy of the object instance, and/or a portion of theobject instance that is determined to inefficiently use memory space anda remainder of the memory space. The presentation apparatus may alsodisplay a memory consumption and padding size of the object instanceand/or a ranking of object instances in the software program bypotential memory savings.

In addition, one or more components of computer system 1200 may beremotely located and connected to the other components over a network.Portions of the present embodiments (e.g., analysis apparatus, virtualmachine instance, presentation apparatus, etc.) may also be located ondifferent nodes of a distributed system that implements the embodiments.For example, the present embodiments may be implemented using a cloudcomputing system that improves the knowledge and management of memoryconsumption in a set of remote software programs.

The foregoing descriptions of various embodiments have been presentedonly for purposes of illustration and description. They are not intendedto be exhaustive or to limit the present invention to the formsdisclosed. Accordingly, many modifications and variations will beapparent to practitioners skilled in the art. Additionally, the abovedisclosure is not intended to limit the present invention.

What is claimed is:
 1. A method, comprising: obtaining a memory layoutfor an object instance in a software program, wherein the memory layoutcomprises a set of offsets and a set of allocated sizes of a set ofcomponents associated with the object instance; using the memory layoutto determine, by a computer system: a first memory space occupied bydata in the object instance; and a second memory space occupied bypadding in the object instance; and displaying a visualization of thememory layout on the computer system, wherein the visualizationcomprises a first graphical distinction between the first memory spaceand the second memory space, wherein components in the object instancethat cause padding are flagged, thereby facilitating more efficientmemory utilization in subsequent programming; and generating arefactored memory layout that consumes less memory by reorganizing thememory layout to reduce the second memory space occupied by padding;wherein the memory layout is associated with an execution context forthe software program, and wherein the method further comprises obtainingan additional memory layout for a non-local execution context by:configuring a virtual machine instance to operate within the non-localexecution context; providing a set of logical representations of theobject instance to the virtual machine instance, wherein the logicalrepresentations are used by the virtual machine instance to generate theadditional memory layout; and obtaining the additional memory layoutfrom the virtual machine instance.
 2. The method of claim 1, furthercomprising: displaying a memory consumption and a padding size of theobject instance on the computer system.
 3. The method of claim 1,further comprising: using the memory layout to determine, by thecomputer system: a first field associated with a first level of aninheritance hierarchy of the object instance; and a second fieldassociated with a second level of the inheritance hierarchy; andincluding a second graphical distinction between the first and secondfields in the visualization.
 4. The computer-implemented method of claim1, wherein the first graphical distinction comprises a difference intransparency between the first and second memory spaces.
 5. Thecomputer-implemented method of claim 1, wherein the graphicaldistinction comprises a difference in color between the first and secondmemory spaces.
 6. The computer-implemented method of claim 1, whereinthe first memory space comprises: a header; metadata; and one or morefields.
 7. The computer-implemented method of claim 1, wherein providingthe visualization of the memory layout to the user comprises: displayingthe first and second memory spaces in a grid based on the set of offsetsand the set of allocated sizes.
 8. A method, comprising: obtaining amemory layout for an object instance in a software program, wherein thememory layout comprises a set of offsets and a set of allocated sizes ofa set of components associated with the object instance; using thememory layout to determine, by a computer system: a first fieldassociated with a first level of an inheritance hierarchy of the objectinstance; and a second field associated with a second level of theinheritance hierarchy; and displaying a visualization of the memorylayout on the computer system, wherein the visualization comprises afirst graphical distinction between the first and second fields, whereincomponents in the object instance that cause padding are flagged,thereby facilitating more efficient memory utilization in subsequentprogramming; and generating a refactored memory layout that consumesless memory by reorganizing the memory layout to reduce the secondmemory space occupied by padding; wherein the memory layout isassociated with an execution context for the software program, andwherein the method further comprises obtaining an additional memorylayout for a non-local execution context by: configuring a virtualmachine instance to operate within the non-local execution context;providing a set of logical representations of the object instance to thevirtual machine instance, wherein the logical representations are usedby the virtual machine instance to generate the additional memorylayout; and obtaining the additional memory layout from the virtualmachine instance.
 9. The method of claim 8, further comprising: usingthe memory layout to determine, by the computer system: a first memoryspace occupied by data in the object instance; and a second memory spaceoccupied by padding in the object instance; and including a secondgraphical distinction between the first and second memory spaces in thevisualization.
 10. The method of claim 8, wherein the first graphicaldistinction comprises a difference in transparency between the first andsecond memory spaces.
 11. The method of claim 8, wherein the graphicaldistinction comprises a difference in color between the first and secondmemory spaces.
 12. The method of claim 8, wherein providing thevisualization of the memory layout to the user comprises: displaying thefirst and second fields in a grid based on the set of offsets and theset of allocated sizes.
 13. The method of claim 8, wherein the firstfield is owned by a first class in the inheritance hierarchy and thesecond field is owned by a second class that is a superclass of thefirst class in the inheritance hierarchy.
 14. A non-transitorycomputer-readable storage medium storing instructions that when executedby a computer cause the computer to perform a method, the methodcomprising: obtaining a memory layout for an object instance in asoftware program, wherein the memory layout comprises a set of offsetsand a set of allocated sizes of a set of components associated with theobject instance; determining, from the memory layout: a first memoryspace occupied by data in the object instance; and a second memory spaceoccupied by padding in the object instance; providing a visualization ofthe memory layout to a user, wherein the visualization comprises a firstgraphical distinction between the first memory space and the secondmemory space, wherein components in the object instance that causepadding are flagged, thereby facilitating more efficient memoryutilization in subsequent programming; and generating a refactoredmemory layout that consumes less memory by reorganizing the memorylayout to reduce the second memory space occupied by padding; whereinthe memory layout is associated with an execution context for thesoftware program, and wherein the method further comprises obtaining anadditional memory layout for a non-local execution context by:configuring a virtual machine instance to operate within the non-localexecution context; providing a set of logical representations of theobject instance to the virtual machine instance, wherein the logicalrepresentations are used by the virtual machine instance to generate theadditional memory layout; and obtaining the additional memory layoutfrom the virtual machine instance.
 15. The non-transitorycomputer-readable storage medium of claim 14, the method furthercomprising: determining, from the memory layout: a first fieldassociated with a first level of an inheritance hierarchy of the objectinstance; and a second field associated with a second level of theinheritance hierarchy; and including a second graphical distinctionbetween the first and second fields in the visualization.
 16. Thenon-transitory computer-readable storage medium of claim 14, the methodfurther comprising: identifying, from the memory layout, aninefficiently used portion of the first memory space; and including athird graphical distinction between the inefficiently used portion and aremainder of the first memory space in the visualization.
 17. Thenon-transitory computer-readable storage medium of claim 14, wherein thefirst graphical distinction comprises a difference in transparencybetween the first and second memory spaces.
 18. The non-transitorycomputer-readable storage medium of claim 14, wherein the graphicaldistinction comprises a difference in color between the first and secondmemory spaces.